Yes, but the 'background threads' are usually not working on the UI. So it's not rocket science to just coordinate access to the tree. It'd be nice to have an

Yes, but the 'background threads' are usually not working on the UI. So it's not rocket science to just coordinate access to the tree. It'd be nice to have an architectural way of doing that, but frankly, just living with the idiom ("Don't Do This") works well, and some frameworks put in runtime checks, i.e. QT will crash I think in some cases if you try to mess with the tree on the wrong thread.